Process for the removal of an embedding body from the embedded component

ABSTRACT

A process and an arrangement are disclosed for the removal of a low-melting embedding body from a higher-melting embedded component. A groove is provided along a molding-in base of the component and by means of the widening of the groove via heatable elements, the resulting halves of the embedding body are removed. The process and the arrangement are particularly suitable for separating embedded guide and moving blades from the manufactured embedding body.

BACKGROUND AND SUMMARY OF THE INVENTION

The invention relates to a process and an arrangement for the removal ofan embedding body made of a lower-melting material from an embeddedhigher-melting metal component or ceramic component.

It is known that embedding bodies of this type consisting of low-meltingmetal alloys or thermoplastics are cast around metal components orceramic components of complicated shapes in order to embed thesepartially so that the embedded part can be chucked or fixed in machineswhile the unembedded part can be machined.

A known process for the removal of these embedding bodies from theembedded component is the melting-off of the embedding body in hot oil.This process has the disadvantages of the oil removal, of the necessarysuction-removal of the oil vapors, of the long melting-off period, ofthe washing-off of the oil residues from the component, of the removalof oil residues, for example, from capillary bores in the component, ofthe removal of the washing-off medium and of the vapors of thewashing-off medium, and the related environmental stress.

Another process consists of splitting the embedding body in a press bymeans of two separating bars. This process has the disadvantage thathigh uncontrollable pressures are exercised on the embedded component sothat there is a high risk of rejections, and compact residues of theembedding material must be removed subsequently at certain points whichagain requires oil baths.

It is an object of the invention to provide a process and an arrangementof this type which ensures a low-residue removal of the embedding bodywhich does not stress or deform the embedded component while the risk ofrejections is reduced at the same time and the means used in the processare less stressful to the environment.

This object is achieved by a process in which the following steps arecarried out:

a. placing a groove in the embedding body along the molding-in base ofthe embedded component; an

b. removing of the halves of the embedding body from the embeddedcomponent by widening the groove along the molding-in base.

This process overcomes the disadvantages of the previous process andsaves considerable waste removal costs since no oil is used. Inaddition, the costs with respect to rejections are reduced since theembedding body is removed from the embedded component under the effectof minimal force after the providing of a groove, for example, bymilling, sawing or grinding.

By means of a preferable melting-out of the groove, even advancing andcutting forces as well as abrasion marks of a possible cutting-in of thegroove are advantageously avoided.

The melting-out has the additional advantage that arbitrary and alsobent or curved groove cross-sections can be made in one operationbecause only the shape of the melting-out tool must be adapted to thecross-section of the groove.

A preferred embodiment of the process provides a melting-out attemperatures of between 50° and 350° C., preferably between 130° and180° C. The large temperature range has the advantage that alsothermoplastics may be used as the embedding material. In a narrowerrange, low-melting metals can be used as the embedding material, such asthe metal alloy tin/bismuth with 30 to 70 percent in weight of bismuth.

The difference between the melting temperature of the embedding materialand the melting temperature of the embedded component should be at least150° C. so that a possible local overheating of the component isavoided.

The embedding and removal is preferably used for components made of anickel, cobalt or titanium base alloy from which guide blades or movingblades of axial-flow turbines and axial-flow compressors are made. Inthis case, the blade base and the blade tip can be machined while thefinished blade with its capillary bores is chucked in in the embeddedarea.

The removal of the halves of the embedding body created by the providedgroove from the embedded component may preferably take place by apulling-apart, turning-apart, pushing-apart, pressing-apart orblowing-apart. This has the advantage that the halves of the embeddingbody are removed from the component without any large formation ofresidues. The finishing of the component is therefore minimized.

As far as the arrangement for carrying out the process is concerned, theobject is achieved in that the arrangement has at least one heatableelement which, in its dimensions, corresponds to the cross-section ofthe groove to be provided, and is arranged so that it can be moved in atleast one direction in space and be rotated around at least onedirection in space, and has a receiving device for the embedding body.

This arrangement has the advantage that it does not apply the groove ina cutting but in a thermal manner and thus has an extremely gentleeffect on the embedded component so that damage to the component islargely avoided In addition, it does not require any fast-rotating toolsso that it has a long service life and can be produced at lowmanufacturing costs.

As the melting-out tool, the arrangement has a heatable element whichadvantageously can be adapted to any desirable groove cross-section.

A preferred development of the heatable element provides that it iselastically mounted so that, during the melting-out, the tip of theheatable element can follow the contour of the embedded componentwithout the requirement of any adjustment. This self-adjustment permitsa complete dividing of the embedded body in two halves along themolding-in base so that these halves fall apart without an expenditureof force, for example, by being blown by a jet of compressed air.

If the component is embedded such that it projects out of the embeddingbody on two opposite sides, the arrangement preferably has two heatableelements in the form of two hot rods which simultaneously melt out agroove on the front edge and the rear edge of the component so that themelting-out operation is shortened and the productivity of thearrangement is increased.

Another preferred development of the arrangement has a blade-shapedheatable element the blade of which completely fills in the requiredgroove along the front edge or rear edge of a correspondingly shapedembedded component in the embedding body with the exception of a meltinggap. This melting gap is created automatically by the flowing-off of themelted-off embedding body material along the wall of the groove. Thispreferred development of the invention has the advantage that themelting-out operation is shortened further.

A further reduction of the melting-out time is achieved by means of anarrangement which preferably has two blade-shaped heatable elementswhich simultaneously fill in the whole groove on the front and rear edgeof an embedded component, the arrangement making it possible that thegroove is not melted out all the way to the component. Although thisrequires a higher expenditure of force during the removal of theembedding-body halves, it has the advantage that during the melting-outof the groove no melted material can penetrate into capillary bores orslots of the component.

In a preferred development, the heatable elements are arranged such thata groove is created which is vertical or which extends up to a slope of60° with respect to the vertical line. An arrangement of this typeensures the discharge of the molted-open embedding material into a drippan without any additional auxiliary measures, such as the turning ofthe embedding body for the throwing-out or flowing-off of the meltedmass.

The arrangement is preferably controlled digitally so that it can beused advantageously in mass production.

Other objects, advantages and novel features of the present inventionwill become apparent from the following detailed description of theinvention when considered in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 represents the principle of an arrangement for carrying out theprocess of the invention by means of heating rods;

FIG. 2 is a sectional view A--B of the arrangement according to FIG. 1;and

FIG. 3 represents the principle of an arrangement for carrying out theprocess by means of heated blades.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 represents the principle of an arrangement for carrying out theprocess by means of heating rods 1 and 2 which simultaneously expose thefront edge 4 and the rear edge 5 on a moving blade 3 made of a nickelbase alloy with a melting point of 1,330° C. In the process, two grooves6 and 7 are melted out of a cuboid-shaped embedding body 8 made of atin/bismuth alloy having a melting point of 137° C. During the verticalupward movement in the directions of arrows 9 and 10, the heating rods 1and 2, by means of their semicircular points 11 and 12, are pressedagainst the front edge 4 and the rear edge 5 of the moving blade 3 bymeans of the spring bearings 13 and 14. After the complete melting-outof the two grooves 6 and 7, the embedding body 8 breaks apart into twohalves which are removed from the moving blade 3.

FIG. 2 illustrates a section A--B of the arrangement according to FIG.1, the guide blade 3 being visible in its profile and being touched bythe two heating rods 1 and 2 at its front edge 4 and rear edge 5, whilegrooves are melted out of the embedding body 8 in the area of theheating rods 1 and 2.

FIG. 3 illustrates the principle of an arrangement for carrying out theprocess by means of heated blades 15 and 16 which are melted into theembedding body in the direction of the arrows 17 and 18. In the process,the melted-off embedding material 19 flows into the drip pan 20 and maybe reused. The heated blades 15 and 16 may be stopped shortly beforethey reach the front edge 4 and the rear edge 5 if a minimal residualweb of embedding material is to protect the front edge 4 and the rearedge 5 of the moving blade 3 from damage or from the penetration ofmelted mass into capillary bores and slots. After the melting-out of thegrooves at the front edge 4 and the rear edge 5, the halves of theembedding body 8 may be removed from the moving blade 3 by a mechanicalwidening of the grooves.

Although the invention has been described and illustrated in detail, itis to be clearly understood that the same is by way of illustration andexample, and is not to be taken by way of limitation. The spirit andscope of the present invention are to be limited only by the terms ofthe appended claims.

What is claimed is:
 1. A process for the removal of an embedding material of low-melting metal from an embedded higher-melting metal component or ceramic component, comprising the steps of:a) forming grooves in the embedding material along spaced position to follow a contour of the embedded component, and b) widening the grooves in the embedding material along the spaced portions and c) removing the embedding material from the embedded component.
 2. A process according to claim 1, wherein the forming of the grooves is achieved by the melting-out of the embedding material.
 3. A process according to claim 1, wherein the forming of the grooves is carried out by the melting-out of the embedding material at temperatures between 50° and 350° C.
 4. A process according to claim 1, wherein the embedding material is a metal alloy made of tin and bismuth with 30 to 70 percent in weight of bismuth into which a groove is melted at temperatures between 130° C. and 180° C.
 5. A process according to claim 1, wherein the embedding material is a thermoplastic material into which a groove is melted at temperatures between 50 to 130° C.
 6. A process according to claim 1, wherein the embedding material is removed from metal components or ceramic components with a melting point of above 500° C.
 7. A process according to claim 1, wherein the process is used for removing embedding bodies from components made of nickel, cobalt or titanium base alloys.
 8. A process according to claim 1, wherein the component from which the embedding material is removed is in the form of guide blades or moving blades of an axial-flow compressor or an axial flow turbine.
 9. A process according to claim 1, wherein the step of widening of the grooves in the embedding material forms two halves of the embedding material, and wherein, for the removal of the two halves of the embedding material from the embedded component, the halves are separated by being one of pulled apart, turned apart, pushed apart, pressed apart and blown apart.
 10. A process according to claim 1, wherein the step of forming the grooves is carried out by melting-out of the embedding material at temperatures between 130° and 180° C. 